HVAC Unit Sizing Chart: What Unit Size Do You Need?

HVAC Unit Sizing Chart: What Unit Size Do You Need?

Heating, ventilation, and air conditioning (HVAC) units are machines that vary in size and work to cool and heat air, allowing you to keep a comfortable and even temperature in your home, office, or building. These units are an essential part of a building’s internal structure that require installation of the correct size of HVAC equipment and proper ductwork to provide a sufficient amount of cool or warm air. If you do not use the right size of equipment for your home or office, there is a risk of inefficiency, unnecessary costs, and inhabitable environmental conditions. 

Why does HVAC size matter? 

Though you could use an HVAC unit that is not sized correctly for your home, it will not work as efficiently or effectively to deliver the high-quality performance that you will want and expect. Imagine using a handheld fan in a living room or an industrial fan in a coat closet – this is how the performance of an HVAC unit is affected when you do not have the right size. It is important for the energy output to be correct or you run the risk of a costly bill or a unit that shuts on and off constantly. 

In order for your home or office space to promote optimal airflow throughout each room, the HVAC unit must work efficiently. When it is too small or big, the machine can not produce an adequate amount of warm or cool air to create a comfortable space. Uneven distribution of air temperature in your house or certain rooms in your home can be a result of a unit that is not the right size. You can end up paying more each month for your HVAC unit to run when it can not cool or heat a room to the temperature that you want. The unit will continue to work until it reaches the set temperature but if your HVAC system is not the right size, it can take a longer amount of time to get there. 

During humid conditions, air conditioning is needed to mitigate mold and prevent growth that could pose a health hazard in a building. Air conditioning units not only cool down the air, but also dehumidify it which prevents mold from growing. If mold growth continues because of incorrect HVAC sizing, it can become uninhabitable. Overall, an HVAC unit promotes livable conditions when you have the right size and properly maintain it. 

As you know, HVAC units also provide heat throughout homes and offices which is important in cold climates. Heat prevents pipes from freezing and bursting during those cold winter months. If an HVAC unit is too small, it may not be able to keep your house or office space warm enough to prevent a freeze from happening. 

What does BTU stand for?

British Thermal Units (BTUs) are a measurement of energy determined by how much heat is required to raise the temperature of a pound of water by one degree Fahrenheit. Finding the right size HVAC unit for your home is dependent on a variety of factors and each home will have a BTU rating to help determine which size is best for your space. These ratings show how much energy is used by your unit per hour to cool down a space. To properly cool and heat your home, your HVAC unit will need to have a certain output of energy which is why knowing the BTU rating is important. 

How to find the right AC unit

The right AC unit can make the world of a difference in your home. There are three types of units to choose from: traditional split-system air conditioner, ductless air conditioner, and packaged air conditioner. Though these are very similar since their main purpose is to cool and heat your home, they function differently. 

The traditional split-system air conditioner has two different units that work together to provide high-quality performance and have high energy efficiency. This type of air conditioning unit does not require a window and is fairly easy to install in your home. With an overall low cost and easy maintenance, it is easy to see why it is used in many homes. There is an indoor and outdoor unit, which is why it is called a split system, and each part plays a significant role in cooling and controlling the humidity level in your building. The outdoor unit contains the condenser and compressor while the indoor unit has an evaporator, furnace, air handler, and filters. Prices for traditional split system air conditioners range from around $4,000 to $9,000. 

A ductless air conditioner often called a mini-split system, is similar to a split system where it contains both indoor and outdoor components. As the name implies, a ductless air conditioner does not require ductwork as refrigerant lines are installed instead. Since the outdoor unit can be attached to multiple indoor units, you can keep rooms in your home at a different temperatures which is why they are very popular. Ductless air conditioners are mostly used for individual rooms instead of an entire home or building. They also vary greatly in price (because you can get them for multiple rooms in your home) but the average cost is around $12,348. 

Packaged air conditioner systems have an outdoor unit without an indoor unit attachment. Instead of splitting all the parts needed to cool your home down, this one unit contains it all in one. The evaporator coil, compressor, and condensing coil uses the ductwork throughout your home or office to cool it down. The unit is usually used in large homes or buildings because of how quickly it can cool down a space. Packaged air conditioners cost an average of $6,800 to $8,000 including installation. 

How to find the right AC unit size

There are two ways to determine which AC unit size is right for your home — the Manual J calculation or a square footage measurement. Both options provide you with the BTU rating, which is the primary piece of information that you are looking to determine. 

The Manual J calculation method is considered the most accurate way to find the BTU rating because it considers a variety of factors in its calculation. Square footage, climate, ductwork, windows, and sunlight are considered during a Manual J calculation. You will also need to know the amount of insulation, the number of people regularly inside, and even information about the heat-generating appliances throughout the home. Developed by the Air Conditioning Contractors of America (ACCA), the Manual J calculation is the most favored approach to determine the BTU rating and load calculation for your HVAC unit. If you are getting your equipment installed professionally, you can ask for an energy audit from the utility company to ensure a correct BTU rating. With this rating, you will be able to find the right size AC unit. Manual J calculations can be tricky to do on your own and will cost you which is why we suggest leaving it up to the professionals for the most accurate reading. 

The following is a rough estimation of the cooling capacity a cooling system would need to effectively cool a room/house based only on the square footage of the room/house, as provided by EnergyStar.gov.

Area To Be Cooled (square feet) Capacity Needed (BTUs per hour)
100 to 150 5,000
150 to 250 6,000
250 to 300 7,000
300 to 350 8,000
350 to 400 9,000
400 to 450 10,000
450 to 550 12,000
550 to 700 14,000
700 to 1,000 18,000
1,000 to 1,200 21,000
1,200 to 1,400 23,000
1,400 to 1,500 24,000
1,500 to 2,000 30,000
2,000 to 2,500 34,000

Consult with a professional

To find the best size HVAC unit for your home, building, or room, it is best to consult with a professional. A professional team can take proper measurements and readings of your home to determine which unit size and air conditioning unit type is best for your particular case. 

Our crew at Advantage Mechanical Supply can help you outfit your home with the right HVAC system. As the leading supplier of air ventilation and heating products, Advantage Mechanical Supply is fully equipped to help you with projects both big and small — we have products that are ready to ship with no fees so that you are able to get all HVAC and ductwork supplies in one place at competitive market prices that are hard to find elsewhere. Submit your project bids to our team today and watch your vision come to life through the hands trustworthy and experienced professionals.
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